thread bench for Ruby

gistfile1.rb

require 'benchmark'
r = 1_000_000
rsqr = r*r
iteration = 10_000

threads= []
mutex = Mutex.new
cnt = [0, 0]

puts Benchmark.measure {
16.times do
  t = Thread.new do
    iteration.times do
      x = rand(2*r) - r
      x = x*x
      y = rand(2*r) - r
      y = y*y
      i = (x+y) / rsqr
      mutex.synchronize do
        cnt[i] = cnt.at(i) + 1
      end
    end
  end
  threads << t
end
threads.each do |t|
  t.join
end
num = cnt[0] * 4
den = iteration * 16

puts Benchmark::CAPTION
puts num / den.to_f
}